The fight is being set for Dec. 8 and Mexican promoter Fernando Beltran, who has close ties with Top rank chief Bob Arum, said it is "95 percent" that the fight will happen.
Also in the running is Tim Bradley, but the US fighter's anemic showing on pay-per-view the night he stunned Pacquiao with a split decision only drew around 700,000 buys.
But Marquez is said to be the hot favorite to get the lead role as Pacquiao's dancing partner owing to his pay-per-view track record.
The Pacquiao-Marquez third fight last year generated 1.4 million subscriptions.
Miguel Cotto of Puerto Rico was also considered but he opted to meet Austin Tout of the US on Dec. 1 at Madison Square Garden in New York.
While it appears that everything points to a fourth showdown between Pacquiao and Marquez, whose rivalry stretches back to May 2004, the main attraction has not actually said anything about the match.
Pacquiao has kept mum about plans about his next fight and the only time he allowed himself to be quoted was when there were efforts to reach a deal for a megabuck encounter with Floyd Mayweather three weeks ago.
So, until Pacquiao doesn't say so, everything remains hanging in the balance.
"Manny was not mentally focused when he fought Bradley," said Lainez. "If Manny trains like hell and gives his 100 percent mentally and physically, he'll beat Bradley in an impressive manner."
Bradley was awarded a controversial 12-round split decision last June 9 even though 99 percent of those who watched the fight live and elsewhere thought he didn't deserve the verdict.
Lainez said that if Pacquiao is training his sights on a megabuck matchup with Floyd Mayweather next year, he should avoid the counter-punching Marquez.
"It's just his (Marquez's) style," said Lainez, noting that the Mexican apparently has got Pacquiao's number.
Cebu kingmaker Wakee Salud echoed the same sentiment.
"Manny should pick Bradley and sacrifice pay-per-view," said Salud, aware that such a pairing wouldn't click in pay-per-view as evidenced by its poor showing last June.
Salud said that while a Marquez fight promises to make a killing, the risk of losing to the 39-year-old Marquez should be of paramount importance.
"Yeah, a Marquez fight will be great for pay-per-view but the risk is high," noted Salud.
Pacquiao is still weighing his options as his decision would have a direct effect on whether the Mayweather fight would take place or not.
